I can only speak to your first topic. You need to remember what the things were designed for, and that was not music in the home. They project exceptionally well, with not much subtlety, but very efficiently. Just the thing for filling a theater space. IMO, they're hard to beat for reproducing the horns in the triumphal march in Aida.
The sectorial horn was available in two sizes, 511B and 811B, with 500 and 800 Hz crossovers, respectively, though both used the 802D driver. The low frequency driver should be an 803B.
As a stab at topic 3, the actual A7, as I knew it, was pretty much an open box with the LF driver mounted at the end of a small front loaded horn, a sort of quite open bass reflex arrangement below, with either the 511B or 811B and 802D mounted on top. There were so many of these in commercial use that I would expect servicing to be available.
We used A7s mostly in the lab, but I did have one at home for some time.
Altec still supplies parts(diaphragms/woofer re-coning kits) for the drivers to all their authorized repair/warranty stations. Waldom Electronics supplies re-coning shops everywhere, and parts that will make the woofer LOOK original, but it will lack the edge-wound aluminum voice-coil(and quite a bit of performance). SO- Yes, thet are easily serviced/supported. The sound: They're LOUD! Comparison with modern horn-loaded theatre systems: They're LOUD too! Some people like LOUD and don't mind the horn colorations/crazy response curves that go with these systems. If you can get them cheaply enough: See if they fit your tastes(they'll be great, if you have neighbors you hate, or for a home theatre system).
Here's a link to the system's PDF manual: (http://www.altecpro.com/pdfs/vintage/SpeakerAndMics/systems/A7-8G%20VOTT%20Speaker%20System%20Manual.pdf) and these guys do the authorized repairs: (www.greatplainsaudio.com)
Picked up a pair of Altec Valencia Bs about ten years ago,still have them. Same driver compliment,only 8 ohms. This started a fire in me and I am always scouring the used/consignment pro audio stores for bargains. The best one here in town does not recognize these for home use.I have since picked up a pair of Altec 902 drivers,Mantaray horns,JBL 2205 woofers and Apt supertweeters that I used to build speakers in a used pair of Altec Santana cabinets I bought on Craigslist.All told I have about $600.invested,I have seen the horn drivers alone sell for that.The biggest improvement came from biamping these.The had a used TDM crossover that had been sitting around for a long time,probably because it had rca jacks.Things like this are worth almost nothing to a pro audio store,so they are great places to look.Horns get a bad rap because they are very revealing of amplification,you should consider using tubes if you get these. Even the mighty Klipschorn will sound god awful with a cheap japanese receiver! I use single ended triodes on the horns and solid state on the bass. This may be a little more complicated than what you would care to go through,but you can have a lot of fun and the results are worth it.I assume because you are willing to put up with their size you are a bit of a putterer like me. I thank companies like Avant Garde and the Edgarhorn for the resurgence of interest in horns,even though they don't use compression drivers.They look cool! Certainly not as intimate and seamless as my Merlin VSM Ms were,but a whole lot more like live music!
As a supplement to my previous post, I might mention that I "graduated" from the A7 to a pair of AR3a speakers in the early 60s, i.e. from monaural to stereo. In our psychoacoustics lab, A7s were driven by the lab standard Mac MC 60 amp, but the efficiency of the A7 suggests that was overkill. I much preferred the big 511B horn with its 500 Hz crossover to the 811B.
Although the 511B and 811B are sectorial horns themselves, the A7 isn't a LF horn design in the sense of the large corner horns in vogue in the time of monaural, e.g. those from Paul Klipsch, JBL, Electrovoice. These were mostly rear loaded LF horns designed to be placed in a corner where the walls could act as extensions of the horn. Their popularity went out with stereo, because you could rarely find a configuration of corners that would work for stereo, and taking the speakers out of the corner removed a major design parameter. IIRC, the smoothness and frequency extension of the dome tweeter of the ARs contributed to the demise of the HF horns.
I looked in the Audiogon Blue Book and didn't see anything about the early A7s, so I'd guess following the ads is the way to figure out what's a fair price.
My impression of the sound of the A7s, with over a 40 year gap, compared to my KEF Reference 104/2s, is that the A7s lack refinement. But then that was not the design goal of the A7s, spreading a lot of sound over a large area with high speech intelligibility was. Usually, A7s were hung close to the ceilings in theaters and auditoriums.
Thank you very much for your inputs. I am going to pick up a pair and let you know how they work with my class A 2A3 push pull and single ended 300B. My room is 36X40X9. The biggest issue is to pick them up in Indiana and i live in MN. The owner just dont want to deal with the packing and shipping. I got a quote from a professional mover for $700.00 and the A7's is about $1000. The total is about $1700.00.
You should find them a very easy speaker to drive. You haven't mentioned whether the A7s have the 811B or 511B sectorial horn. In looking over an Altec brochure from that time, I see the A7 spec is for the 811, although we had both in the lab. I hope you are aware the A7 is an industrial looking box intended to be custom finished for residential use. Their top of the line residential unit at the time was the Laguna, with two 803B LF drivers and a 511B horn with 802D HF driver. List price was $599; list price of the A7 was $299.40. By the way, one of the features mentioned in the brochure is ease of driving the speakers without the need for high powered amps.
I also have an interesting booklet by Badmaieff, Altec's chief acoustics and transducer engineer, in which he discusses speaker enclosure design principles. In my high school days, I built a few enclosures based on Altec designs and populated them with Altec drivers.
I own a pair of A-7's since last fall and love them. I have run them with 3/4 of a watt and 75 watts. Depending on your room size and listening habits I recommend caution in terms of power, especially if they are 16 0hm like mine. 75 watts was a pair of Blue Circle BC2 hybrid monoblocks, 3/4 of a watt ( That's right not even a full watt! )was a custom Darling amp and lastly a custom 45 SET both made by P. Townsend a retired electronics engineer/designer/extraordinaire.
These need clean low hum/noise amps. More than 2.5
milivolts from 12 feet away and you will hear it when music stops or possible quiet passages.
1. The sonic signature of the A7's? Dynamics and texture matched by few. (Tannoy?)
2. How much they worth? 700-3,500 Japanese worship A-7's
3. Can they still be serviced? Great Plains Audio http://www.greatplainsaudio.com/
4. How are they compare with modern speakers if this is a fair question?
Depends on how much care you show in amp choice and minor simple tweeks to cabinets and (damping)horn. Will exceed most modern designs in dynamics, texture, finesse and natural reproduction elegance.
My uncle owns a pair that he built in the 60's, I believe, and they are still some of the best speakers I have ever had the pleasure of listening to. His was the first truly high-end system I ever experienced. Go for it!
Hey, Ginas, I'd take the comments of Spl and Learsfool with a grain of salt. Finesse and texture are not terms that come to mind as I recall the A7. One only has to consider their design aim and common application: Auditorium sound. You might like them, but honky comes to mind. Of course, I've mostly heard them with Mac MC 60 amps -- we balanced the tubes on those very closely; as a grad student that was one of my jobs.
Dbphd, if by finesse you mean a more "laid-back" presentation (such as say the Sonus Faber line, for example), then no, the horns are not going to give you that. However, they are much more revealing of the various textures in the music than any other type I have ever heard. And they were not designed only for auditorium use, many people have used them in their homes for decades. Too much amplification would indeed ruin them, they are designed for low amplification, but matched with the right amps, they can be wonderful. All of those great orchestral recordings made on the Mercury label were famously mastered using those very A7's driven with MacIntosh amplification, for instance, similar to what you describe in your post. There is surely a reason they used that combo for such richly textured music! Yes, this is old school thinking, but I have yet to hear a high amplification/low sensitivity speaker combo come remotely close to matching the stunning realism of a great horn speaker/low powered tube amp combo.
I am one of those people who used an A7-500 and MC 60 in my home, when I was a graduate student and the A-7s were being surplused. As I previously noted, hard to beat for the horns in the triumphal march of Aida, but not my choice for a string quartet.
They can sound great with string quartet given SET amps or low wattage quality Push Pull. I've even driven mine with a 50 watt Accuphase with astounding results. Yes, to much power and mediocre electronics can make them honk, but this is not a trademark of Altec just poor set up.
And so it goes. Enjoy your A-7s.